"Right now, it doesn't appear to be a life-threatening situation," said National Oceanic and Atmospheric Administration Fisheries Biologist Aleria Jensen.

"With any luck, the net may come loose on its own," she said. "Meanwhile, we will continue to monitor the calf's condition."

Just three weeks ago, NOAA reported the drowning of an adult humpback when its entire body became tangled in a gillnet near Wrangell.

In that case, a fisherman immediately reported the entanglement. But NOAA does not know yet how the calf near Juneau became entangled and is seeking out fishermen who may have lost a gillnet recently .

The entangled calf was first spotted on Monday by a sailboat near the mouth of Gastineau Channel. It was last seen swimming and breathing freely near its mother.

Freeing the calf is virtually impossible at this time because it is entangled through its mouth. "We don't have a technique to pull that gear off," Jensen said.

Another factor making NOAA biologists reluctant to interfere with the calf is caution about how its mother will react if biologists immobilize the calf for disentanglement. "Mom's behavior is unpredictable," Jensen said.

The two have been spotted numerous times this week, circling near the mouth of Gastineau Channel.

NOAA is cautioning boaters to keep a greater distance from the pair than the mandatory 100-yard approach rule for humpback whales.

The species is protected under the Endangered Species Act.

NOAA has mobilized a team of regional whale experts that is on call if the situation becomes critical, Jensen said. Biologists from the University of Alaska and the National Park Service are assisting on the team.

Between 1997 and 2004, NOAA reported 51 humpback whale entanglements in Alaskan fishing gear, most of them involving crab or shrimp pot lines. Only two deaths were reported, though in most cases, the whales' ultimate fate was unknown.

Biologists rarely have success removing gillnets from whales, as the mesh doesn't provide much resistance against cutting tools, according to NOAA.

NOAA Fisheries biologists observed the whales in the water on Tuesday and Wednesday.

They also have been consulting with net disentanglement experts on the East Coast, Jensen said.

Anyone who sees the whale is asked to call NOAA Fisheries at 907-586-7235.

 Elizabeth Bluemink can be reached at elizabeth.bluemink@juneauempire.com.